* מה שלומך בבית הספר? (Mah shlomkha b'Beit ha-sefer?) This literally translates to "How's your well-being at school?" It's a more formal and comprehensive option.
* איך בבית הספר? (Eich b'Beit ha-sefer?) This translates to "How is it at school?" It's a bit more casual.
* מה קורה בבית הספר? (Mah koreh b'Beit ha-sefer?) This means "What's happening at school?" This is quite informal and suitable for close friends or family.
For a child, you might also use a simpler phrase like:
* טוב בבית הספר? (Tov b'Beit ha-sefer?) This translates to "Good at school?" It's a shorter and simpler question suitable for younger children.
The best choice will depend on your audience and the level of formality you want to convey. The first two are generally safe choices for most situations.